iFit barrel adapters solve two problems simultaneously, they can both change your barrel threads, and also greatly improving your barrels accuracy. These adapters are meant to be used with the iFit barrel boring kits, and when used with the proper sized iFit sleeve will lead to a dramatic improvement in accuracy. These are also barrel thread adapters, and can be used to put different threaded barrels on your favorite gun. On the adapters the first gun mentioned in their product name is the marker you are putting the barrel on, and the second thread type will be for the threads of the barrel you are putting on your marker.